hello my name is Kylie and welcome to earthquakes volcanoes and tsunamis in
this video you'll learn about all the parts of the earth and how it shakes
rattles and blasts let's get down to earth
seen from space planet Earth is composed of land and
water but did you know that the earth is made up of more than what the eye can
see the surface of the earth where we live is called the crust it is actually
a thin layer of rock underneath the crust is a layer of very hot sometimes
melted or molten rock called the mantle and at the very center of the earth
there is the core the deeper into the earth we go the hotter it gets the core
is actually made up of two parts the outer core and the inner core the outer
core is made up of molten or melted rock and it is like the texture of pudding
and the inner core is solid
speaking of solid let's take a hard look at natural events that have shaped land
over time although we don't feel it the surface of the earth or the crust is
always moving the continents drift apart and the oceans move too by rising and
falling over time all of the earth's movements have caused the crust to break
up these broken up pieces of surface rock are called tectonic plates because
they are like gigantic plates floating on the Earth's mantle these plates
moving caused the continents to drift also known as continental drift
geologists or scientists who study the earth mapped out the seven major
boundaries of the Earth's tectonic plates they include the Pacific plate
the North American plate the Eurasian Plate the African plate and the
Antarctic plate also the indo-australian plate and the South American plate
that's a lot of plates did you know that mountains and volcanoes are formed
because of these plates moving and did you know that earthquakes are caused by
these plates crashing together I know it's earth-shattering depending
on where you live you might have already experienced an earthquake or two
earthquakes our shifts of the tectonic plates when the plates collide they
scrape against each other really violently and create trembles and shakes
on the Earth's crust called an earthquake imagine two very hard
surfaces trying to slide past each other but they are not going to glide smoothly
like liquids do their force is so great that they can actually cause intense
shockwaves through the surface of the earth sometimes causing a lot of damage
to entire cities
why couldn't the two tectonic plates be friends because there is too much
friction between them the plate edges that bang up against each other are
called fault lines you may have heard that the place is most likely to have
earthquakes are those along fault lines that's why some states or provinces have
more chances of earthquakes than others the San Andreas Fault that's where I
live is a fault line that runs through California and is 750 miles long there
are three main types of faults strike-slip fault normal fault and
reverse faults strike-slip faults are rocks sliding past each other
horizontally or side-to-side the San Andreas is a strike-slip fault
normal faults are two blocks of crust spreading apart to create a space or a
valley such as the Basin and Range province in the western USA and reverse
faults are when one block of crust is thrust above another these types of
faults are found where tectonic plates push up mountain ranges like in the
Rocky Mountains or the Himalayas don't worry it's not your fault if you can't
remember all this information at once you'll get a chance to practice later
scientists who study earthquakes are called seismologists and they use a
scale to measure the force of an earthquake this scale is called the
Richter scale and it measures the intensity or magnitude of earthquakes on
a scale of one to ten where one is not powerful and 10 is tremendously
destructive you might sometimes hear that an earthquake measured 6.2 on the
Richter scale this means depending on how long it quaked the damage to a city
can be quite serious earthquakes have aftershocks or a series of smaller
tremors that happen following a really large earthquake we know
that they're actually aftershocks and not another earthquake because they
occur in the same area and zone as a major earthquake did just at a lower
magnitude this focus point or the point where the earthquake first starts is
called the epicenter here's a fun fact every hour the earth quakes about 900
times but most of them cannot be felt by humans because they are minor itty bitty
quakes whoo tectonic plates are constantly shifting
also which causes other things to happen to the earth when magma or molten rock
from the Earth's mantle pushes the surface of the earth the pressure of the
magma forms domes or mountains some mountains have a giant hole in it
because the pressure of the magma is so strong when this happens it creates what
we know of as a volcano the heat and high pressure in the magma chambers
causes an eruption the molten rock is forced up the volcanoes pipe and pours
out to opening or crater of the volcano when magma reaches the Earth's surface
it's called lava lava is like a river of fire that flows out of the volcano and
open throws pieces of rock and ash in the air
it also spews out gases and poisonous fumes not all volcanoes are the same
some are dormant or extinct because they have not erupted in centuries some
volcanoes are younger than others and some are flat and not dome shaped at all
there is a major Zone in the basin of the Pacific Ocean where many volcanoes
and earthquakes occur it's called the Ring of Fire
because it's an enclosed area shaped like a horseshoe
you can visit volcanoes around the world like in Costa Rica Japan and even in the
USA did you know that the Hawaiian Islands are actually volcanoes that
started underwater and have grown through eruptions over many years what
on earth
yeah it's true both volcanoes and earthquakes can happen underwater - when
tectonic plates shift the shaking of the ocean floor causes the water to rise so
high that it creates a high wall of water known as a tsunami tsunamis grow
in size the closer and closer they get to shore and it can rise as high as a
hundred feet that's higher than a seven story building Wow some people confuse
tidal waves with tsunamis but they are not the same tidal waves which are high
sea waves can be caused by tsunamis but they can also be caused by storms and
very strong winds because of underwater volcanic activity the ocean floor
actually spreads this is called seafloor spreading and it happens slowly over
time along the mid-ocean ridges a mid-ocean ridge is an underwater
mountain system that is formed by plate tectonics each year the ocean floor is
known to spread one to two inches a rare phenomenon that can catch you by
surprise if you are near a volcano is a geyser a
geyser is a vent on the Earth's surface that lets out a forceful jet of water
into the air Old Faithful is a geyser located in Yellowstone National Park in
Wyoming and it erupts every forty five to a hundred and twenty-five minutes
whether inside or on the surface the earth is vibrating with natural forces
that can happen at any time to practice what you've learned about earthquakes
volcanoes and tsunamis be sure to play our fun online games and quizzes until
next time remember to always be clever